The present invention relates to low insertion loss connection of an antenna to a mobile radio, and more particularly to low insertion loss connection of an antenna to a satellite telephone.
In non-satellite transceivers, such as conventional cellular telephones, a connection to an external vehicular antenna can be made through a radio frequency connector normally located on the bottom of the telephone. In order to prevent both the phone antenna and the external vehicular antenna from radiating radio frequency energy at the same time, which can cause phasing and other problems, a radio frequency switch in the conventional cellular telephone switches internal connections from the telephone antenna to the external vehicular antenna connected to the frequency connector, when a connection is detected.
In satellite transceiver applications, such as in satellite telephones, the use of a radio frequency switch for the purpose of switching internal connections from the phone antenna to the external vehicular antenna is not desirable due to the high insertion loss of the radio frequency switch. This high insertion loss is particularly problematic in satellite telephones because of the limited loss budget due to the greater distance between the satellite telephone and an earth orbit satellite with which it communicates. In order to make up this loss on the satellite side, by building a more sophisticated satellite, extremely high costs would be involved, such as on the order of 40 million dollars.
One way in which to eliminate the radio frequency switch is to simply use a detachable connector to connect the phones antenna to the satellite telephones, and when use of the external vehicular antenna is desired to remove the telephone antenna and to connect vehicular antenna to the site on the satellite telephone from which the phone antenna was removed. This approach is, however, awkward and time consuming, and therefore not highly desirable.
Another approach is to employ an inductive coupler that, when the satellite telephone is inserted into a docking adaptor in the vehicle, surrounds the telephone antenna (or a portion thereof) providing an inductive link between the external antenna and the satellite telephone. This approach, however, fails to achieve direct contact or close capacitive coupling between the vehicular external antenna and the satellite telephone, and thus also suffers from high insertion loss.
The present invention advantageously addresses the above and other needs.